ASoC: sigmadsp: safeload should not have lower byte limit

Fixed range in safeload conditional to allow safeload to up to 20 bytes,
without a lower limit.

Signed-off-by: Danny Smith <dannys@axis.com>
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>